How to handle realloc when it fails due to memory?

Question

Question says it all but here is an example:

typedef struct mutable_t{
    int count, max;
    void **data;
} mutable_t;


void pushMutable(mutable_t *m, voi         


        

Answer 1

The strategy about what to do when realloc() fails depends upon your application. The question is too generic to be answered for all possible cases.

Some other notes:

Never do:

a = realloc(a, size);

If realloc() fails, you lose the original pointer, and realloc() does not free() the original memory, so you will get a memory leak. Instead, do:

tmp = realloc(a, size);
if (tmp)
    a = tmp;
else
    /* handle error */

Second point I want to make is minor and may not be that critical, but it's good to know about it anyway: increasing the memory to be allocated by a factor f is good. Let's say you malloc() n bytes first. Then you need more memory, so you realloc() with size n×f. Then you need more memory, so you need n×f² bytes. If you want realloc() to use the space from the previous two memory blocks, you want to make sure that n×f² ≤ n + n×f. Solving this equation, we get f≤ (sqrt(5)+1)/2 = 1.618 (the Golden ratio). I use a factor of 1.5 most of the times.